Exercise Snacking And Detraining Effects On Postprandial Glucose Responses - A Randomized Crossover Trial In Trained Older Adults

Abstract

PURPOSE: Experimental data suggest that frequent interruptions in sedentary behavior (SB) promote improvements in postprandial glucose (PPG) responses. However, little is known about the impact of these interruptions before and after a detraining period in active older adults. The main purpose of this investigation was to examine the acute effects of interrupting prolonged SB in a sample of trained older adults, before and after 2-weeks of detraining, on PPG. METHODS: Older active adults performing structured exercise at least 2/week for the past 6 months (n=14; aged between 65 and 90 years-old), were enrolled in a randomized crossover trial. Participants performed two conditions before and after 2-weeks of detraining (i.e. refrain from structured exercise): 1) uninterrupted sitting, where participants remained seated throughout 7 hours (SIT); 2) Sitting + moderate intensity breaks (INT), where participants were instructed to sit for 7 hours, while interrupting this behavior with 2 minutes of moderate-intensity physical activity (PA) every 30 minutes. The primary outcome was changes in PPG, while body composition and cardiorespiratory fitness (CRF) were considered secondary outcomes. Generalized estimating equations (GEE) were used. SUMMARY OF RESULTS: Both at baseline and after detraining, no differences were observed for 7-h total area under the curve (7h-AUC) for glucose (baseline: ∆ -3.1%, p = 0.542; post-detraining: ∆ -8.8%, p = 0.182) and mean glucose (MG) values (baseline: ∆ -3.3%, p = 0.541; post-detraining: ∆ -9.0%, p = 0.188) between INT and SIT experimental conditions. An unfavorable effect was observed for the SIT condition from baseline to after the detraining period, with higher values for 7h-AUC (∆ 10.6%, p = 0.014) and MG (∆ 11.7%, p = 0.015). No changes were observed in the response to INT condition between baseline and after detraining in PPG values (7h-AUC: ∆ 4.4%, p = 0.535; MG: ∆ 5.2%, p = 0.523). CONCLUSION: Frequent interruptions in SB had no effect on PPG, prior to or after a 2-week detraining period, when compared to prolonged SB in active older adults. On the contrary, older adults experiencing a short-term detraining period can use strategies, such as breaking up SB, in order to potentially improve glycemic control during these intermissions.